1. Field of the Invention
This invention relates to an improvement in burners for waste materials and particularly to an improvement in the quench system of a fluidized bed incinerator for waste materials such as sludge obtained from biotreatment of sewage.
2. Prior Art
Incineration of waste material in fluidized bed incinerators is an established commercial practice.
A patent which discloses a two-stage fluidized bed incinerator and a method for operating it is U.S. Pat. No. 3,306,236 to Campbell. While the present invention may be practiced in a single stage fluidized bed incinerator, the Campbell patent may be referred to for general principles of fluidized bed waste incineration.
A detailed description of a fluidized bed incineration system for petroleum refinery wastes is presented in a publication of the Environmental Protection Agency Water Quality Office. The publication is No. 12,050 EKT 03/71 of the Water Pollution Control Research Series, entitled "Fluid Bed Incineration of Petroleum Refinery Wastes by American Oil Company -- Mandan Refinery", available from the Superintendent of Documents, U.S. Government Printing Office, stock number 5501-0052. This publication describes the use a fluidized bed incinerator of the type to which the present invention is particularly applicable. The incinerator described in that publication is one developed by the Copeland Process Corporation of Oakbrook, Ill.
In employing a fluidized bed incinerator for the treatment of the sludge obtained in biotreatment of chemical process wastes, a serious problem was encountered in the case of those wastes in which the sludge contained a large amount of fusible salts. The conventional incinerator provided for injection of sludge feed, quench water, and air into the top of the incinerator vessel. It was found that the injection of quench water into the top of the vessel led to the agglomeration of the sand and ash entering the vapor removal duct and to frequent rapid plugging of the duct, requiring shut-down of the incinerator and laborious clean-up of the vapor removal system.